docs: def new_page(self, page_number, new_chapter, **kwargs):
          """Called by :meth:`render` with the :class:`Chain`s that need more
          :class:`Container`s. This method should create a new :class:`Page` which
          contains a container associated with `chain`."""
          right_template = self.document.get_page_template(self, 'right')
          left_template = self.document.get_page_template(self, 'left')
          page_template = right_template if page_number % 2 else left_template
          return page_template.page(self, page_number, self.chain, new_chapter,
                                    **kwargs)